The present invention relates to a method for supporting the treatment of a patient by means of a navigation system. Such navigation systems detect and track the positions of patients, parts of the patient""s body, and targets of treatment as well as of treatment devices, and show, in many cases, the surgeon concerned images on a monitor, which he uses to support his treatment.
In this connection, problems may arise in the course of treatment if the tissue is subjected to shifting during treatment, as may happen, for example, due to liquid discharge or removal of tissue. In such a situation, i.e. if the target of treatment or the surrounding tissue together with the target of treatment has been shifted, the supporting navigation becomes inaccurate, with the result that the surgeon involved is again entirely left to his own observations or, if he did not notice the shift, might possibly operate at wrong positions.
It is therefore an object of the present invention to provide the treating surgeon with a means enabling him to still navigate precisely by means of a navigation system even after tissue has been shifted during an operation.
According to the invention, this object is solved by a method as set forth in claim 1. Advantageous embodiments of the inventive method are described in the sub-claims.
The advantages of the method in accordance with the invention are particularly based on the fact that, in addition to the data record the navigation system has used up to that moment, one or several further current patient data records are created, either automatically or on demand, by an image-generating method, and that each current data record is integrated into the navigation system in a computer-aided manner. It is, thus, not only ensured that a new and current data record, recording the cited tissue shifts and changes, is available at a given time, but the current data record will simultaneously be linked or integrated into the navigation system so that the surgeon concerned is able to continue his work quickly with the assistance of a precisely integrated and updated navigation support. Accordingly, incorrect treatment can be avoided, and the surgeon concerned no longer has to depend on visually perceiving large-scale tissue removals or liquid discharges.
The other data record/s of the patient can be created during the operation by means of different methods. These are, in particular, magnetic resonance tomography (MR), computer tomography or the SPECT or PET methods.
In a first specific embodiment of the method according to the invention, a reference structure is positioned at the patient or in the surrounding area of the target of treatment while the current data record is being created, said reference structure comprising markers which can be detected by the navigation system as well as markers which can be detected by the image-generating method, the assignment of data for the markers resulting in a positional integration of the current data record into the navigation system. According to another, but similar, embodiment, the reference structure comprises markers detectable in the navigation system as well as by the image-generating method.
Accordingly, the reference structure and the markers thereof are the point of intersection for the assignment of the current data record into the navigation system. Due to the positional detection of the navigation system marker, the navigation system knows the position of the reference structure and, furthermore, its position is known in the newly created data record, as here markers are also detected at the reference structure. Similarly, the image-generating system also knows the position of the pixels and can detect/compensate the deviations between the individual data records of the patient (caused by different positions of the patient) and/or transmit them to the navigation system. Thus, each subsequently following data record is automatically referenced, i.e. only the first data record has to be localized/referenced, provided that the patient is firmly fixed, e.g. by means of a rigid head fixation.
According to another specific embodiment of the inventive method, the new data record can be integrated into the navigation system in that the current data record is assigned, as concerns the position, to the data record to be updated by means of a computer-aided, automatic, three-dimensional image fusion, referencing of the current data record occurring in the navigation system from the computed positional shift. Both data records, i.e. the one already available in the navigation system and the current data record from the image-generating device, which both supply three-dimensional image data, may be brought into conformity with each other by means of what is known as image fusion by a suitable computer program. If this could have been reached with sufficient conformity, one can gather from this that one transformation that leads from the data record to be updated to the current data record, and by means of such a transformation, the neuro-navigation system may be set anew and to the current state and the current positioning of the tissue to be treated. This method is especially advantageous as no further means are required; updating can be done on demand, e.g. by pressing a button. Similarly, the above-described image fusion can, of course, also be started automatically without any user actions being required.
With regard to the above-referenced method, it is possible to proceed in such a manner that the image fusion is, at least partially, solely based on those data record elements from the current data record and the data record to be updated, which do not reflect any, or just a restricted, deformation of the detected part of the body. This option is especially useful to reduce computing times and to avoid larger errors if rigid transformations, as will be described later, cannot supply valid results any more.